1. Field of the Invention
The present invention relates to a mechanism for use in a can opener that may be provided with a manual or automated drive means.
Metal cans are a well-known form of packaging for preserved goods and generally comprise a cylindrical wall portion closed at both ends with a circular lid. The lid is usually fixed in place by providing an upstanding rim around the edge of the lid which is bent down in an inverted U-shape for clamping onto the end of the cylinder.
2. Related Background Art
Two basic types of can opener are commonplace. The first type relies on making a circular cut around the lid near its edge typically within the upstanding rim. The second type relies on using a circular cutter knife to make a cut around the cylindrical wall portion of the can. Typically, the cut is made near the edge of the cylindrical part of the can but just below the lid so that when a complete circular cut is made, the lid and a small portion at the end of the cylindrical part of the can and rim is removed. One advantage of this second type of can opener is that its cutter knife is designed to give a clean cutting action as opposed to a tearing action which typically is found with can openers of the first type.
United Kingdom Patent application No. GB 2 118 134 A1 describes a can opener of the second type comprising a pair of handles which are hinged to one another to be movable between an open position for fitting onto a can and a closed cutting position; a manually rotatable drive wheel which engages the rim of a can and upon rotation advances the opener around a can; and a circular cutting wheel brought to a cutting position relative to the drive wheel as the handles are brought to the closed position. The circular cutting wheel is rotatably mounted on one handle with its axis displaced from the axis of hinging. The other handle has an upstanding cylindrical spigot extending through a corresponding hole in the one handle and about which the one handle is hinged relative the other handle. A support for the drive wheel passes through and is rotatably born in the spigot with the axis of rotation of the drive wheel displaced from the axis of the spigot.
Can openers of the general type described in the GB 2 118 134 A1 document have been widely marketed for a number of years under the trade mark Lift Off. Various improvements to such can openers have been described in later patent applications including Canadian patent application No. CA 1 200 086 A1; and European patent applications Nos. EP 0 193 278 A1, EP 0 202 790 A1 and EP 0 574 214 A1.
One problem with the can opener of GB 2 118 134 A1 and of its later variations is that two separate kinds of actions are required to achieve the cutting function. Firstly, the two handles must be brought together, typically by a manual squeezing action. Subsequently, rotary drive must be provided to the drive wheel. The Applicant has appreciated that such requirement for these two separate kinds of actions makes it difficult to fully automate a can opener of this type. Indeed, the GB 2 118 134 A1 document only envisages manual operability.
In solution to this problem, Applicant has now devised a can opener mechanism, which relies only on the provision of rotary drive, preferably to a single drive wheel. Such rotary drive may be provided by manual or automatic (i.e. powered) drive means.